SRT Hydrology and River Hazards 3

Question 1

When reading a river, what does an upstream-pointing V between rocks indicate?

Accepted Answer

A submerged rock or obstruction just below the surface

Answer

An upstream-pointing V (pointing toward you as you face downstream) indicates converging currents caused by a submerged rock or obstruction beneath the surface.

Question 2

What is 'laminar flow' in the context of river hydraulics?

Accepted Answer

Water flowing in parallel layers with minimal mixing between layers

Answer

Laminar flow occurs when water moves in parallel layers with little disruption between them, typically found in slow, deep, smooth sections of a river.

Question 3

Which principle explains why water flows faster in the center of a river channel than near the banks?

Accepted Answer

Hydraulic radius and boundary friction reducing velocity near channel edges

Answer

Friction from the riverbed and banks slows water near the edges and bottom, so velocity is greatest away from these boundaries, typically at center and surface.

Question 4

A rescue swimmer enters an eddy to stage for a live-bait rescue. What current direction will they encounter when crossing the eddy line?

Accepted Answer

A sudden shift from upstream-moving eddy current to faster downstream main current

Answer

The eddy line is a shear zone where the upstream-moving eddy current meets the faster downstream main current, requiring the rescuer to lean and anticipate the force change.

Question 5

What does the term 'hydraulic gradient' refer to in river hydrology?

Accepted Answer

The drop in elevation of the riverbed per unit of horizontal distance

Answer

Hydraulic gradient (or river slope) is the vertical drop divided by horizontal distance, directly influencing current velocity — steeper gradients produce faster water.

(SRT) Swiftwater Rescue Technician Certification Practice Test

(SRT) Swiftwater Rescue Technician Certification Practice Test

SRT Hydrology and River Hazards 3